how to don't initialize object is some of the properties is nil decodable

To handle the initialization of an object in Swift when some properties might be nil, you can use a failable initializer. A failable initializer allows you to return nil if the initialization cannot be completed due to some invalid or missing data. This is particularly useful when dealing with optional properties.

Here's a brief explanation based on the content from WWDC:

In Swift, you can create a failable initializer by using the init? syntax. This initializer can return nil if any of the required properties are not available or valid. This approach is useful for preventing resource leaks or invalid states when initializing objects.

For example, if you have a file type that should only be initialized if a valid file name is provided, you can use a failable initializer to ensure that the object is only created when all necessary conditions are met. This is discussed in the session What’s new in Swift.

Additionally, Swift's optionals are designed to handle cases where a value might be absent. You can use optional binding with if let or guard let to safely unwrap optionals and handle the case where a property might be nil. This is covered in the session A Swift Tour: Explore Swift’s features and design.

By using these techniques, you can ensure that your Swift code is robust and handles all possible states of your objects.